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Date:      Thu, 27 Sep 2007 23:18:01 -0500
From:      Eric Schuele <e.schuele@computer.org>
To:        freebsd-current@freebsd.org
Subject:   Trouble with GDB and specific app on 7.0-CURRENT....
Message-ID:  <46FC8079.6030304@computer.org>

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Hello,

I have a particular app that I am unable to debug using gdb.  When I
attach to the app and continue it, gdb begins to take up 100% of my cpu.
 It will do this forever (well longer than I've ever waited).

I am able to debug this particular app on my 6.2-STABLE machine.  And I
can debug other apps on my 7.0 machine.  I've tried both gdb 6.1 and gdb
6.6 on my 7.0 machine with no change in behavior.

I first thought maybe I had done something odd when rebuilding my
kernel/world?  But I've built a second 7.0 machine and stuck with the
GENERIC kernel and I have the same results.

Most times I can not break into the app once I have continued it.  I
have attached gdb to gdb to watch what it is doing and it appears to
give me a few different backtraces, though it is always one of maybe
three traces.  [See below for bt of gdb attached to gdb, unfortunately
its not the same bt I was seeing... but may offer some insight?]

Has anyone seen behavior like this?  What else can I provide that might
help diagnose this?

--=20
Regards,
Eric

Backtrace of gdb =3D=3D> gdb
#0  0x2874cbbb in ptrace () from /lib/libc.so.7
#1  0x08068b42 in i386fbsd_resume (ptid=3D{pid =3D -1, lwp =3D 0, tid =3D=
 0},
step=3D0,
    signal=3DTARGET_SIGNAL_CHLD) at i386fbsd-nat.c:76
#2  0x080ed0de in resume (step=3D0, sig=3DTARGET_SIGNAL_CHLD) at infrun.c=
:626
#3  0x080f05ed in keep_going (ecs=3D0xbfbfe544) at infrun.c:2892
#4  0x080ef284 in handle_inferior_event (ecs=3D0xbfbfe544) at infrun.c:20=
21
#5  0x080ed63e in wait_for_inferior () at infrun.c:1009
#6  0x080ed46a in proceed (addr=3D4294967295, siggnal=3DTARGET_SIGNAL_DEF=
AULT,
    step=3D0) at infrun.c:827
#7  0x080ea249 in continue_command (proc_count_exp=3D0x0, from_tty=3D1)
    at infcmd.c:642
#8  0x0808082b in do_cfunc (c=3D0x28977190, args=3D0x0, from_tty=3D1)
    at .././gdb/cli/cli-decode.c:62
#9  0x08082e6d in cmd_func (cmd=3D0x28977190, args=3D0x0, from_tty=3D1)
    at .././gdb/cli/cli-decode.c:1666
#10 0x08054cbd in execute_command (p=3D0x2890c081 "", from_tty=3D1) at to=
p.c:455
#11 0x080feadf in command_handler (command=3D0x2890c080 "c") at
event-top.c:519
#12 0x080ff307 in command_line_handler (rl=3D0x2895b112 "c") at
event-top.c:804
#13 0x28319826 in rl_callback_read_char () from /lib/libreadline.so.7
#14 0x080fe1cf in rl_callback_read_char_wrapper (client_data=3D0x0)
    at event-top.c:179


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